The vapor pressure of water at a certain temperature is $3000 \ N \ m^{-2}$. When a non-electrolyte solute is added,it decreases by $300 \ N \ m^{-2}$. The molality of the solution is ............. $m$.

Lowering of vapour pressure due to a solute in $1 \, molal$ aqueous solution at $100 \, ^\circ C$ is ........ $torr$.

What is the vapour pressure of a solution when $2 \ mol$ of a non-volatile solute are dissolved in $20 \ mol$ of water (in $mm \ Hg$)? $(P_1^{\circ} = 32 \ mm \ Hg)$

Vapour pressure in $mm \ Hg$ of $0.1 \ mole$ of urea in $180 \ g$ of water at $25^{\circ} C$ is (The vapour pressure of water at $25^{\circ} C$ is $24 \ mm \ Hg$ )

The vapor pressure of pure $A$ is $10 \ torr$. When $1 \ g$ of $B$ is dissolved in $20 \ g$ of $A$ at the same temperature,the vapor pressure of the solution becomes $9 \ torr$. If the molar mass of $A$ is $200 \ g/mol$,the molar mass of $B$ is ............ $amu$.

What will be the molar mass of a non-volatile solute if the vapour pressure of pure benzene is $450 \ mm \ Hg$ and it decreases to $400 \ mm \ Hg$ when $1.5 \ g$ of the solute is added to $30 \ g$ of benzene? (Atomic mass: $C=12, H=1$)